Invitae Hereditary Hemorrhagic Telangiectasia Panel


Test description

This test is for individuals with a clinical diagnosis of hereditary hemorrhagic telangiectasia (HHT). The primary Invitae Hereditary Hemorrhagic Telangiectasia Panel includes four genes that are definitively associated with HHT.

Individuals with clinical symptoms of HHT may benefit from diagnostic genetic testing to establish or confirm diagnosis, clarify risks, or inform management. Asymptomatic members of a family with a known HHT pathogenic variant may also benefit by avoiding specific medications (e.g., anticoagulation and anti-inflammatory agents) that can trigger symptoms.

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Primary panel (4 genes)


Add-on preliminary-evidence gene (1 gene)

Preliminary-evidence genes currently have early evidence of a clinical association with the specific disease covered by this test. Some clinicians may wish to include a gene which does not currently have a definitive clinical association, but which may prove to be clinically significant in the future. This gene can be added at no additional charge. Visit our Preliminary-evidence genes page to learn more.


Hereditary hemorrhagic telangiectasia (HHT)

Hereditary hemorrhagic telangiectasia (HHT) is a vascular dysplasia characterized by the presence of multiple arteriovenous malformations (AVMs), an abnormality of the development of arterial and venous vessels, which result in direct connections between arteries and veins due to the lack of intervening capillaries. Small AVMs that occur near the skin surface and are markedly visible are known as telangiectasias. Individuals with HHT are at risk for spontaneous and recurrent nosebleeds (epistaxis) and hemorrhages in the brain, liver, lungs, or other organs.

This test covers the most common genetic causes of HHT. Pathogenic variants in ENG and ACVRL1 account for 60%-80% of clinical HHT cases. The remaining genes on this panel account for an unknown proportion of HHT cases.

HHT is an autosomal dominant condition.

HHT exhibits age-related penetrance, meaning individuals who inherit a predisposition to develop HHT will have an increased manifestation of symptoms over their lifetime. Most individuals with HHT present with age-related symptoms, typically occurring at or after adolescence. Because HHT is a developmental disorder, severely affected infants have also been reported. Variable expression has been reported within families as well.

The prevalence of HHT is between 1 in 5,000 and 1 in 10,000 people.

This test may be considered for individuals with:

  • presence of multiple arteriovenous malformations (AVMs)
  • presence of spontaneous and recurrent nosebleeds (epistaxis) and mucocutaneous telangiectases

For links to published management guidelines, please refer to our Management guidelines page.

Assay and technical information

Invitae is a College of American Pathologists (CAP)-accredited and Clinical Laboratory Improvement Amendments (CLIA)-certified clinical diagnostic laboratory performing full-gene sequencing and deletion/duplication analysis using next-generation sequencing technology (NGS).

Our sequence analysis covers clinically important regions of each gene, including coding exons, +/- 10 base pairs of adjacent intronic sequence, and select noncoding variants. Our assay provides a Q30 quality-adjusted mean coverage depth of 350x (50x minimum, or supplemented with additional analysis). Variants classified as pathogenic or likely pathogenic are confirmed with orthogonal methods, except individual variants that have high quality scores and previously validated in at least ten unrelated samples.

Our analysis detects most intragenic deletions and duplications at single exon resolution. However, in rare situations, single-exon copy number events may not be analyzed due to inherent sequence properties or isolated reduction in data quality. If you are requesting the detection of a specific single-exon copy number variation, please contact Client Services before placing your order.

Gene Transcript reference Sequencing analysis Deletion/Duplication analysis
ACVRL1 NM_000020.2
ENG NM_000118.3
GDF2 NM_016204.2
RASA1 NM_002890.2
SMAD4 NM_005359.5